Perovskite quantum dots doped nematic liquid crystal composites: Influence on dielectric parameters and electrical conductivity

IF 5.2 2区化学 Q2 CHEMISTRY, PHYSICAL

Journal of Molecular Liquids Pub Date : 2025-09-23 DOI:10.1016/j.molliq.2025.128597

Nidhi , Jai Prakash , Shikha Chauhan , Gautam Singh

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引用次数: 0

Abstract

In the current study, we have reported the dispersion of inorganic perovskite quantum dots i.e., CsPbBr₃ PQDs in a cyanobiphenyl based nematic liquid crystal i.e., 5CB (4՛-pentyl-4-biphenylcarbonitrile) at different concentrations (0.1 wt%, 0.25 wt%, 0.5 wt%, and 1.0 wt%) and its effect on the dielectric and electrical parameters of the latter. The polarized optical micrographs were obtained for confirming the uniform and stable dispersion of PQDs in 5CB. Frequency dependent dielectric parameters (ε′, ε″, tan δ) were measured in the range of 20 Hz to 2 MHz using the dielectric spectroscopy. A higher value of ε′ was attained and a corresponding relaxation peak in ε″ and tan δ appeared due to the electrode polarization in low frequency region for composite system. The relaxation process was analyzed using Havriliak-Negami (HN) equation indicating a Debye-type relaxation in this region. The parallel component of permittivity has a lower value for PQDs-5CB composites than the Pure 5CB sample, while the perpendicular component does not change significantly and hence, dielectric anisotropy decreases when PQDs were mixed in LC matrix. Electrical conductivity was evaluated and found to be increased due to higher ionic density for composites. The DC conductivity was calculated by fitting the electrical conductivity data with Jonscher Power Law. The activation energy was computed using the Arrhenius equation. These results suggest that PQDs can be availed as a guest material for modulating the physical properties of LCs making them more efficient for tunable electronic devices.

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钙钛矿量子点掺杂向列液晶复合材料：对介电参数和电导率的影响

在目前的研究中，我们报道了无机钙钛矿量子点，即CsPbBr3 PQDs，在不同浓度（0.1 wt%, 0.25 wt%， 0.5 wt%和1.0 wt%）的氰联苯基向列液晶，即5CB （4 -戊基-4-联苯碳腈）中的分散，以及它对后者的介电参数和电学参数的影响。为证实PQDs在5CB中的均匀稳定色散，获得了偏振光学显微照片。在20 Hz ~ 2 MHz范围内，利用介电光谱测量了频率相关的介电参数ε′、ε″、tan δ。由于电极在低频区极化，复合体系的ε′值较高，ε″和tan δ出现相应的弛豫峰。利用Havriliak-Negami （HN）方程分析弛豫过程，表明该区域存在debye型弛豫。PQDs-5CB复合材料的介电常数平行分量比纯5CB样品低，而垂直分量变化不明显，因此PQDs在LC基体中混合后介电各向异性降低。电导率进行了评估，发现由于较高的离子密度的复合材料增加。利用Jonscher幂定律拟合电导率数据，计算直流电导率。利用阿伦尼乌斯方程计算活化能。这些结果表明，pqd可以作为调制lc物理性质的客体材料，使其更有效地用于可调谐电子器件。

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来源期刊

Journal of Molecular Liquids 化学-物理：原子、分子和化学物理

CiteScore

10.30

自引率

16.70%

发文量

2597

审稿时长

78 days

期刊介绍： The journal includes papers in the following areas: – Simple organic liquids and mixtures – Ionic liquids – Surfactant solutions (including micelles and vesicles) and liquid interfaces – Colloidal solutions and nanoparticles – Thermotropic and lyotropic liquid crystals – Ferrofluids – Water, aqueous solutions and other hydrogen-bonded liquids – Lubricants, polymer solutions and melts – Molten metals and salts – Phase transitions and critical phenomena in liquids and confined fluids – Self assembly in complex liquids.– Biomolecules in solution The emphasis is on the molecular (or microscopic) understanding of particular liquids or liquid systems, especially concerning structure, dynamics and intermolecular forces. The experimental techniques used may include: – Conventional spectroscopy (mid-IR and far-IR, Raman, NMR, etc.) – Non-linear optics and time resolved spectroscopy (psec, fsec, asec, ISRS, etc.) – Light scattering (Rayleigh, Brillouin, PCS, etc.) – Dielectric relaxation – X-ray and neutron scattering and diffraction. Experimental studies, computer simulations (MD or MC) and analytical theory will be considered for publication; papers just reporting experimental results that do not contribute to the understanding of the fundamentals of molecular and ionic liquids will not be accepted. Only papers of a non-routine nature and advancing the field will be considered for publication.